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powerpc/vfio_spapr_tce: Add reference counting to iommu_table

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So far iommu_table obejcts were only used in virtual mode and had
a single owner. We are going to change this by implementing in-kernel
acceleration of DMA mapping requests. The proposed acceleration
will handle requests in real mode and KVM will keep references to tables.

This adds a kref to iommu_table and defines new helpers to update it.
This replaces iommu_free_table() with iommu_tce_table_put() and makes
iommu_free_table() static. iommu_tce_table_get() is not used in this patch
but it will be in the following patch.

Since this touches prototypes, this also removes @node_name parameter as
it has never been really useful on powernv and carrying it for
the pseries platform code to iommu_free_table() seems to be quite
useless as well.

This should cause no behavioral change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Alexey Kardashevskiy 2017-03-22 15:21:50 +11:00 • committed by Michael Ellerman
parent 11edf116e3
commit e5afdf9dd5
7 changed files with 37 additions and 17 deletions
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5
arch/powerpc/include/asm/iommu.h
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@ -119,6 +119,7 @@ struct iommu_table {
struct list_head it_group_list;/* List of iommu_table_group_link */
unsigned long *it_userspace; /* userspace view of the table */
struct iommu_table_ops *it_ops;
struct kref it_kref;
};
#define IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry) \
@ -151,8 +152,8 @@ static inline void *get_iommu_table_base(struct device *dev)
extern int dma_iommu_dma_supported(struct device *dev, u64 mask);
/* Frees table for an individual device node */
extern void iommu_free_table(struct iommu_table *tbl, const char *node_name);
extern struct iommu_table *iommu_tce_table_get(struct iommu_table *tbl);
extern int iommu_tce_table_put(struct iommu_table *tbl);
/* Initializes an iommu_table based in values set in the passed-in
* structure